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Midwestern Wind Turbines Keep Fresh Breeze Over Nearby Crops

Published: December 21st, 2010

Climate In Context

Three things you need to know

-- The U.S. Department of Energy projects that it is possible for the U.S. to get 20 percent of its electricity from wind energy by 2030, if there is a major investment in building the needed infrastructure.

-- Some of the country’s best wind energy resources are found blowing over the rich agricultural lands of the Midwest.

-- Wind turbines set amidst agricultural land in the Midwest refresh the air around the plants, and now researchers are studying how changes in airflow will impact corn and soybean crops.

The Debrief

Wind turbines such as these have been erected across the Midwest recently. Credit: flickr/WindeBabe.

When wind turbine blades absorb energy from the wind to generate electricty, they also channel some airflow down towards the ground. Now, researchers are getting a sense of how air currents change at the ground level near large turbines, fueling speculation about how this might affect crops growing nearby.

Last week at the American Geophysical Union’s annual meeting in San Francisco, Eugene Takle, an agricultural meteorologist from Ames Laboratory at Iowa State University, shared new data (not yet published) showing that at ground level where crops are growing, areas below wind turbines experience more exchange of air than where there aren’t any turbines. Last summer, Takle and his collaborators sampled the air within cornfields that also contain large wind turbines. By measuring the temperature changes, moisture levels, carbon dioxide (CO2) concentrations and wind speeds of the air around crops situated close to wind turbines, Takle and his colleagues showed that the turbines do bring more fresh air to the crops, which means nearby plants may be seeing cooler temperatures and air with more CO2.

With these findings, Tackle and other researchers are now trying to learn how the enhanced air exchange affects the crops, if at all. For example, they speculate that having more air flow around the plants may help speed up the drying of dew that forms on the leaves, which could reduce the growth of damaging molds on the plants. Moreover, it’s possible that with a bit more CO2 getting to the crops, the plants will have more fuel for photosynthesis, boosting growth. These predictions, however, haven’t yet been studied and will be the focus of Takle’s research over the next few summers.

Why this science matters

In 2008, the U.S. Department of Energy released a report claiming it is possible for the U.S. to get 20 percent of its energy from wind power by 2030, but that this would require a major expansion of the current wind infrastructure. Some of the country’s most consistent wind blows across the Midwest, areas that have already been developed for agriculture, but it's not yet clear how turbines can best be incorporated into the Midwestern landscape.

“It’s convenient if we can combine wind turbines with agricultural land,” says Julie Lundquist, an agricultural meteorologist from the University of Colorado at Boulder, “but we need to get a better understanding of what the impact will be on the crops so we can make the right policy decisions.” Lundquist, who also works at the National Renewable Energy Laboratory, collaborated with Takle on the project presented in San Francisco. Right now, Takle and Lundquist are focused on measuring the impacts on crops in the Midwest, but Lundquist says more studies are also needed in other places where turbines might be placed on farmed land, since soil type, rainfall patterns and crop varieties may lead to different results.

Although more research is needed to determine what biological impacts wind turbines may have on crops in the Midwest, Lundquist says there is a separate benefit for farmers who build wind turbines on their land. Wind turbines are a source of guaranteed income for these farmers, she says, which may be especially beneficial in years where the crops don’t fare well.